Tobacco expansion process

ABSTRACT

Tobacco is impregnated with an organic dicarboxylic acid or derivative thereof which is capable of thermal decomposition to form a gas. Thereafter the impregnated tobacco is heated to decompose the compound and form the gas within the tobacco and the tobacco is expanded.

United States Patent [1 1 Frederickson et al.

[ 1 TOBACCO EXPANSION PROCESS [75] Inventors: James D. Frederickson; Ella Sue Hickman; Edward D. Harper, all of Winston-Salem, NC.

[73] Assignee: R. J. Reynolds Tobacco Company,

Winston-Salem, N.C.

[22] Filed: June 1, 1972 [21] App]. N0.: 258,747

Related U.S. Application Data [62] Division of Ser. No. 860,014, Sept. 22, 1969,

abandoned.

[52] U.S. Cl. 131/140 P; 131/133 [51] Int. Cl. A24b 3/18; A24b 15/00 [58] Field of Search 131/140, 140 P [56] References Cited UNITED STATES PATENTS 1/1931 Hawkins ..131/140 P UX 5/1957 Veatch 131/140 P UX [451 May 13,1975

3,364,935 1/1968 Moshy et a1. 131/140 C 3,524,452 5/1970 Moser et a1 1 131/140 3,575,178 4/1971 Stewart .1 131/140 P 3,612,065 10/1971 Rosen 131/143 3,710,803 1/1973 Johnson 131/140 P FOREIGN PATENTS OR APPLICATIONS 1,878,358 8/1963 Germany 131/140 P 1,815,169 12/1968 Germany 131/140 P Primary ExaminerMelvin D. Rein Attorney, Agent, or FirmNeuman, Williams, Anderson & Olson 4 Claims, No Drawings 1 TOBACCO EXPANSION PROCESS This application is a division of our prior application Ser. No. 860,014 filed Sept. 22, 1969, now abandoned.

This invention relates to a process of treating tobacco and has for an object the process for increasing the filling capacity of a tobacco product.

Tobacco leaves when harvested contain a considerable quantity of water and during the normal tobacco curing process this water is removed by drying resulting in shrinkage of the leaf structure. In the usual process of preparing tobacco for storage and subsequent cigar or cigarette manufacture, the tobacco regains very little, if any, of the shrinkage resulting from the drying step so that a significant loss in the filling capacity of the tobacco is the result. Thus, the cured tobacco has a bulk density which is in excess of that required for making satisfactory cigarettes or cigars. Also, during cutting of leaf or strips for making cut filler for cigarettes, frequently the shreds are laminated together to form hard, dense particles which occupy far less volume than the original shreds occupied. This is wasteful since these hard compacted shreds are not necessary in a smoking product to produce a satisfactory article.

Several procedures have been suggested in the prior art for increasing the normal filling capacity of dry or cured tobacco. Certain of these procedures have involved puffing operations in which the tobacco is subjected to high pressure steam, followed by sudden release of pressure. Also, it has been suggested that the filling capacity of tobacco may be increased (i.e., bulk density reduced) by exposing the tobacco particles or fibers to the vapors of an organic liquid or to an organic liquid followed by air drying at ordinary pressures. However, these prior procedures have not been wholly satisfactory either because they are not effective for expanding the filling capacity to any great extent or they result in shattering of the tobacco structure and particles so that considerable waste incident to the formation of fines results.

Accordingly, another object of this invention is the provision of a tobacco treating process which represents an improvement over the above-noted processes.

A further object of this invention is the provision of a process for increasing the filling capacity of tobacco under conditions such that the process can be readily controlled to produce the desired product.

An additional object of this invention is the provision of a process for increasing the filling capacity of tobacco in which elevated temperatures which may adversely affect the quality of the tobacco are avoided.

Further and additional objects will appear from the following description and the appended claims.

In accordance with this invention, a process is provided in which tobacco is impregnated or otherwise intimately associated with an organic compound capable of thermal decomposition to form a gas. Thereafter the treated tobacco is subjected to gas-releasing conditions whereby the compound is decomposed to liberate the gas within the tobacco and the tobacco is expanded and its filling capacity increased. In accordance with this invention, the non-gaseous organic chemical compound is one which is capable of thermal decomposition within the tobacco. The impregnated tobacco is heated for a brief period to a temperature sufficient to cause gas to be liberated directly within the impregnated tobacco. This results in the desired expansion.

At the time of gas release the tobacco should have a sufficiently high moisture content so that the structure of the tobacco is sufficiently flexible or pliable to expand when the gas is released. Generally speaking, the moisture content of the tobacco when subjected to the gas-releasing treatment is in excess of about 10 percent by weight. After the gas has been released it may be separated by heating the tobacco to an elevated temperature or by applying a vacuum to the treated tobacco at a lower temperature. in either event, any excess water may also be removed simultaneously from the expanded tobacco by vaporization.

The tobacco to be treated in accordance with the process of this invention is preferably a cured tobacco and may be in the form of shreds, strips, leaves or stems. However, the process is easier to control and the best results are obtained if tobacco shreds are used. This is for the reason that usually shreds are relatively easy to handle in continuous procedures and the final product of the process need not be subjected to shredding as may be necessary for cigarette manufacture. Shredding of the final product would result in compressing the product which would tend to destroy the ultimate objective of the process of this invention, namely, to expand the tobacco and eliminate compressed particles, as may have resulted from prior treatment including shredding. Any type of tobacco may be used in the practice of this invention and it is particularly useful for the processing of burley, flue-cured and Oriental (e.g., Turkish) tobaccos.

The organic compound which is capable of chemically releasing the gas may be applied to the tobacco in any desired manner. It is preferred that the compound be incorporated into the tobacco in the liquid condition in order that uniform impregnation of the tobacco may be achieved. For example, the compounds may be dissolved in a suitable solvent such as water, alcohol, acetone, a volatile hydrocarbon, a volatile halogenated hydrocarbon, or the like, and then applied by spraying, sprinkling or dipping in any desired manner. In such cases thorough and rapid impregnation may be further assisted if the tobacco is subjected to subatmospheric pressure to expel a portion of the air from the tobacco particle interstices before contacting with the impregnated solution. Under certain conditions the gasreleasing chemical may be formed in situ within the tobacco or may be applied to the tobacco in the dry state as by dusting or otherwise or the gas-releasing chemical, whether liquid or solid, may be incorporated into the tobacco in the micro-encapsulated state.

Any organic compound which is capable of chemical decomposition to release a gas under conditions noninjurious to the tobacco may be employed. Thus, the chemical compound and the conditions of gas release should be such that the smoking quality of the tobacco is not impaired. Also, the compounds and their degradation products should be nontoxic and free from any undesired flavor and aroma-producing substances.

Compounds suitable for use in accordance with this invention may be selected from a wide variety of known organic compounds. These are those which will thermally decompose at a relatively low temperature within the impregnated tobacco to release one or more gases such as carbon dioxide, nitrogen, ammonia, carbon monoxide, C to C olefins, etc. These gasreleasing compounds include the organic carbonates such as ethylene carbonate (1,3-dioxolan-2-one), methyl carbonate, ethyl carbonate and di-t-butyl carbonate; the organic dicarboxylic acids and their derivatives and related compounds such as anhydrous oxalic acid, oxamic acid, methoxalic acid anhydride, dimethyloxalate, di-t-butyloxalate, urea oxalate, the malonic acids, citric acid and the B-ketoacids', and the salts, amides, esters and other derivatives of azodicarboxylic acid such as azobisformamide and diethylazodicarboxylate. It will be appreciated that the temperature at which the thermally decomposable compounds will release the gas in the tobacco may in part depend on the constituents of the tobacco and the various other substances that may be present. Thus, with certain compounds small amounts of acids or salts normally found in or added to tobacco may affect the temperature at which gas release will occur and this circumstance will permit the use of some gas-releasing substances whose thermal decomposition temperature, when in the pure state, would otherwise be so high as to adversely affect the quality of the tobacco.

At the time of the expansion of the tobacco by the chemical decomposition of the impregnating com pound, the moisture of the tobacco is preferably at least about percent by weight in order to permit proper expansion of the tobacco particles. However, if water is required for the gas-releasing decomposition reaction per se, the moisture content of the tobacco being treated should be correspondingly increased. During the gas release or immediately thereafter any excess water may be removed by vaporization in order to set the tobacco in the expanded condition. As noted above, this may be done by heating the tobacco with live steam or in a current of a hot dry inert gas, by radiant heating, or by rapid drying under vacuum. The moisture content of the expanded tobacco product may be adjusted, i.e., reordered to between about 10 and percent by weight by conventionalprocedures to produce a product suited for use in the manufacture of cigarettes and for other smoking purposes.

For a more complete understanding of this invention, reference will now be made to the following examples of procedures for carrying this invention into effect.

EXAMPLE 1 One hundred parts by weight of shredded burley tobacco having a moisture content of about 12 percent by weight are uniformly sprayed with 50 parts by weight of a 5 percent alcoholic solution of ethylene carbonate. The sprayed tobacco is retained in a closed container for 1 hour to permit uniform impregnation to occur. A stream of hot air at about 130 C. is passed through the tobacco to vaporize the alcohol, release carbon dioxide and remove a portion of the water. The resulting tobacco has a final moisture content of about 6 percent and has a decreased bulk density. It is reordered to about 13 percent moisture and is suitable for manufacture of cigarettes and other smoking articles.

EXAMPLE 2 One hundred parts by weight of shredded flue-cured tobacco having a moisture content of about 13 percent are sprayed with 10 parts by weight of diethyl azodicarboxylate. After a period of 15 minutes to allow thorough impregnation, the impregnated tobacco is heated in a stream of steam at 140l70 C. whereby carbon dioxide and nitrogen are liberated and the gas and a portion of the moisture are removed. The resulting expanded tobacco product is reordered to about 12 percent moisture and is suitable for use in the manufacture of cigarettes.

EXAMPLE 3 Twenty parts by weight of anhydrous di-t-butyl oxalate dissolved in parts by weight of anhydrous ethyl alcohol are sprayed on 500 parts by weight of shredded fluecured tobacco having a moisture content of about 12 percent by weight. After 20 minutes the tobacco is treated with superheated steam at C. for a period of 2 minutes to release carbon dioxide within the shreds and to expel the gas (i.e carbon dioxide and isobutylene), the alcohol and a portion of the water. The dry resulting product is reordered to a moisture content of about 14 percent.

When applied to shredded tobacco, the process of this invention results in a product essentially free of compressed laminated tobacco particles which are found incident to the initial shredding of the tobacco used as a charge stock. The product may be used to manufacture cigarettes in the conventional manner or it may be mixed with other tobaccos to provide a desired blend for use in the manufacture of cigarettes or other smoking articles.

While particular embodiments of this invention have been described in the foregoing, it will of course be apparent that other modifications may be made without departing from the spirit and scope of this invention.

What is claimed is:

1. A process of increasing the filling capacity of tobacco which comprises impregnating at substantially ambient pressure a mass of discrete tobacco particles in the form of shreds, strips, leaves or stems with an organic dicarboxylic acid or a derivative thereof, rapidly heating the mass of impregnated tobacco to an elevated temperature whereby said organic compound is chemically decomposed to liberate a gas within the individual tobacco particles and said discrete particles are thereby expanded without appreciable disintegration.

2. A process in accordance with claim 1 wherein there is employed oxalic acid or an ester thereof.

3. A process in accordance with claim 1 wherein there is employed malonic acid or an ester thereof.

4. A process in accordance with claim 1 wherein there is employed di-t-butyl oxalate. 

1. A PROCESS FOR INCREASING THE FILLING CAPACITY OF TOBACCO WHICH COMPRISES IMPREGNATING AT SUBSTANTIALLY AMBIENT PRESSURE A MASS OF DISCRETE TOBACCO PARTICLES IN THE FORM OF SHREDS, STRIPS, LEAVES OR STEMS WITH AN ORGANIC DICARBOXYLIC AID OR A DERIVATIVE THEREOF, RAPIDLY HEATING THE MASS OF IMPREGANTED TOBACO TO AN ELEVATED TEMPERAURE WHEREBY SAID ORGANIC COMPOUND IS CHEMICALLY DECOMPOSED TO LIBERATE A GAS WITHIN THE INDIVIDUAL TOBACCO PARTICLES AND SAID DISCRETE PARTICLES ARE THEREBY EXPANDED WITHOUT APPRECIABLE DISINTEGRATION.
 2. A process in accordance with claim 1 wherein there is employed oxalic acid or an ester thereof.
 3. A process in accordance with claim 1 wherein there is employed malonic acid or an ester thereof.
 4. A process in accordance with claim 1 wherein there is employed di-t-butyl oxalate. 